Manage the scheme to the charging of the lead-acid battery on the basis of UC3909 chip

Having the intersection of lead-acid battery and life time badly in need of solution than short and system charge the intersection of ability and insufficient two big problems these under pale terms at present. The lead-acid battery projected life of systematic storing energy component is about three years, but because charging way, storing the way and influence of a great deal of factors artificially,etc. to lead to the fact that its service life is too short, need changing frequently, not only strengthen the use cost also influence the stability of the system. In addition the system that the majority has already use been charges ability under pale terms insufficiently, lead to the fact the stiff utilization factor of systematic solar energy is not high; It is to adopt the configuration and is controlled rationally and realized that the tradition improves the pale method to charge ability, namely adopt the solar energy board assembly of relay control to charge storage battery according to different modes of combination of connecting in series or connecting in parallel etc. according to external illumination power, guarantee the output voltage of board assembly of solar energy reaches and presumes the charging voltage all the time.

Though this kind of method can be realized paly and charged, at the fleeting moment of changing in configuration, the circuit exports voltage fluctuation bigger, influence the system stability. In addition, because of adopting relay control, the mechanical switch contact of the electrical relay is apt to abrade and does not work even cause the fault-operation after the longer time of work. For improve system to be pale to charge ability effectively, literary grace this use super bank of capacitors and go up and down, press circuit, come, realize under pale terms charging effectively, and adopt UC3909 to realize that charge managing to the intellectuality of the colloidal sealing lead-acid storage battery, lengthen the life time of the storage battery.

A lead-acid battery of charge characteristics

The charge characteristic of the lead-acid battery is reflecting by accepting and charging ability in its maximum, it is the maximum charging current born while guaranteeing. It charges characteristic curves equation:

In the type, I is the charging current; I 0 is the charging current of original maximum; a Accepted by maximum the force ratio; t It is charging duration.

In actual the intersection of battery charge and management, want, make charging up of storage battery identical this charge characteristic curves, store relatively loud difficulty in totally. So in line with raising charge efficiency, ensuring the life time of the storage battery, realizing the rational effective charged principle, consult and charge the characteristic curves, adopt the intellectual control chip UC3909 to realize that charge and discharge to the colloidal sealing lead-acid storage battery by stage and control managing.

2, because of UC3909 Four stages of control device charge

It is three-stage charging way that the control device of accumulator charge generally adopts in the solar energy lighting system of separate type at present, namely constant current is charged first, constant voltage charge again, and then floating-charge is charged. But because the storage battery of some application will often present the situation excessively discharging, if relatively charged constant current of the heavy current of direct access charges stage at the beginning, it is apt to cause thermorunaway, the storage battery of vulnerableness. So should adopt the trickle IT charged trickle charge mode when beginning most, wait for the terminal voltage of the storage battery to reach the charging presumed and can enable at the time of the voltage UT, and then charge constant current. UC3909 can until state of storage battery realize trickle charge and constant current charge and constant voltage charge, and floating-charge charge charge rationally 4 stages in chip, as shown in Fig. 1.

Four stage charging curves of Fig. 1 UC3909

The state 1: Trickle charge.

It can enable the voltage UT to charge as the accumulator voltage is lower than, the charger offers very little tiny stream IT to charge, IT is generally about 0. 01C C is the battery capacity The state 2: Constant current is charged.

It can be at the time of the voltage UT to reach and charge enabling in the voltage of the storage battery, the charger offers a high-current I BULK to charge constant current to the storage battery, this stage is charged main stage, the end of storage battery is sharp in voltage build up, enter constant voltage charge stage until voltage build up has been to press the charging voltage UOC.

The attitude 3: Constant voltage charge.

At this stage, the charger offers a voltage UOC slightly higher than the rated value of the storage battery to carry on the constant voltage charge, the charging current of the circuit will be reduced gradually according to the index law, until the electric current magnitude means charging and stopping the electric current I OCT about 10 IBULK ,The storage battery has already been filled, the charger enters the floating-charge charging state.

The state 4: Floating-charge is charged.

Floating-charge charges stage, the charger offers the floating charge voltage UF to flow and charge to the storage battery by very little float charging, in order to remedy the capacity losses that the self-discharge of storage battery causes. Vary with temperature because of the floating charge voltage of the storage battery at the same time, need to choose the thermal resistor of the temperature coefficient the same as storage battery to carry on temperature compensation, guarantee that can charge floating-charge at any temperature with the rigorous floating charge voltage. The temperature coefficient is generally chosen- 3. 5~ – 5 mV/ .

3 charges circuit design

Fig. 2 shows in order that because of U C3909 solar energy battery charger circuit block diagram, the photovoltaic array is sampled and feedbacked the digital signal to the one-chip computer by the analog to digital converter again through the electric current of voltage, the one-chip computer outputs PWM signal to drive PMOS tube according to the operating condition of the photovoltaic array, realize the maximum power tracing of the photovoltaic array. Super condenser bank, DC/ DC converter, UC3909 are used for realizing four stage charge control to the valve controlled lead-acid battery, and utilize the super and capacitive characteristic to optimize the charging/discharging process. This text lays particular emphasis on realizing partly to super condenser bank, U C3909 and DC/ DC converter,etc. that analyzes and designs to the charging at four stages of the valve controlled lead-acid battery.

System block diagram of Fig. 2

3. Main parametric design of 1 UC3909 charger

Based on UC3909 to fill the discharging circuit and is shown as in Fig. 3.

Fig. 3 based on UC3909 serves as the discharging circuit

According to integrated circuit and photovoltaic array within UC3909, and super electric capacity parameter combines the capacity of the valve controlled lead-acid battery and isoparameter of nominal voltage to design rational calculation to each part of the circuit. Originally design using 12 V that Saite Company produced, 65 Ah colloidal sealing lead-acid storage battery, according to the accumulator charge parameter that the producer offers, the floating charge voltage UF fetches 13. 8 V, can make to charge the voltage UT fetch 10. 8 V; Overvoltage charging voltage UOC 14. 7V; The tiny stream charging current I TC fetches 0. 26 A; Constant current charging current I BU LK fetches the systematic maximum charging current 6. 5 A; Overcharged to stop the electric current IOCT fetching 1 A.

In addition, may follow and flow into the fixed control current ITRCK of the reverse Ausgang CA of error amplifier of the electric current within U C3909, the intersection of tiny stream and the intersection of charging current and I T, the intersection of constant current and the intersection of charging current and IBULK and overcharged to terminate the electric current IOCT calculating and obtaining RG1, RG2, R OVC1 and ROVC2, their basic formulae are as follows:

It is installed outdoors that the lead-acid battery in the photovoltaic system is generally stiff with the solar energy, and the change of ambient temperature has great influence on characteristic of the lead-acid battery, research indicates, the float charging of the lead-acid battery flows to having extremely sensitive temperature, the temperature is 10 of every change, float charging flows and doubles and redoubles, as to the storage battery used in this design, according to the parameter that the producer offers, the same float charging flows, its temperature coefficient is – 3. 9 mV/ Centigrade degree, that is to say that if prevents float charging from flowing and increasing, when the temperature raises 1, its floating charge voltage should be reduced by 3. 9 mV ; The same, when the temperature is reduced by 1, its floating charge voltage should raise 3. 9 mV could keep float charging flowing constantly.

Compensator circuit of 4 lead-acid batteries of temperatures of Fig.

Have integrated the circuit with temperature compensation function of the lead-acid battery and is shown as in Fig. 4 within U C3909, A1 is the electric current / voltage transition element, its input end connects 10 k ordinary resistance and 10 k thermal resistor respectively. A2 and connecting four pieces of 20 k resistance to make up

Having the intersection of lead-acid battery and life time badly in need of solution than short and system charge the intersection of ability and insufficient two big problems these under pale terms at present. The lead-acid battery projected life of systematic storing energy component is about three years, but because charging way, storing the way and influence of a great deal of factors artificially,etc. to lead to the fact that its service life is too short, need changing frequently, not only strengthen the use cost also influence the stability of the system. In addition the system that the majority has already use been charges ability under pale terms insufficiently, lead to the fact the stiff utilization factor of systematic solar energy is not high; It is to adopt the configuration and is controlled rationally and realized that the tradition improves the pale method to charge ability, namely adopt the solar energy board assembly of relay control to charge storage battery according to different modes of combination of connecting in series or connecting in parallel etc. according to external illumination power, guarantee the output voltage of board assembly of solar energy reaches and presumes the charging voltage all the time.

Though this kind of method can be realized paly and charged, at the fleeting moment of changing in configuration, the circuit exports voltage fluctuation bigger, influence the system stability. In addition, because of adopting relay control, the mechanical switch contact of the electrical relay is apt to abrade and does not work even cause the fault-operation after the longer time of work. For improve system to be pale to charge ability effectively, literary grace this use super bank of capacitors and go up and down, press circuit, come, realize under pale terms charging effectively, and adopt UC3909 to realize that charge managing to the intellectuality of the colloidal sealing lead-acid storage battery, lengthen the life time of the storage battery.

A lead-acid battery of charge characteristics

The charge characteristic of the lead-acid battery is reflecting by accepting and charging ability in its maximum, it is the maximum charging current born while guaranteeing. It charges characteristic curves equation:

In the type, I is the charging current; I 0 is the charging current of original maximum; a Accepted by maximum the force ratio; t It is charging duration.

In actual the intersection of battery charge and management, want, make charging up of storage battery identical this charge characteristic curves, store relatively loud difficulty in totally. So in line with raising charge efficiency, ensuring the life time of the storage battery, realizing the rational effective charged principle, consult and charge the characteristic curves, adopt the intellectual control chip UC3909 to realize that charge and discharge to the colloidal sealing lead-acid storage battery by stage and control managing.

2, because of UC3909 Four stages of control device charge

It is three-stage charging way that the control device of accumulator charge generally adopts in the solar energy lighting system of separate type at present, namely constant current is charged first, constant voltage charge again, and then floating-charge is charged. But because the storage battery of some application will often present the situation excessively discharging, if relatively charged constant current of the heavy current of direct access charges stage at the beginning, it is apt to cause thermorunaway, the storage battery of vulnerableness. So should adopt the trickle IT charged trickle charge mode when beginning most, wait for the terminal voltage of the storage battery to reach the charging presumed and can enable at the time of the voltage UT, and then charge constant current. UC3909 can until state of storage battery realize trickle charge and constant current charge and constant voltage charge, and floating-charge charge charge rationally 4 stages in chip, as shown in Fig. 1.

Four stage charging curves of Fig. 1 UC3909

The state 1: Trickle charge.

It can enable the voltage UT to charge as the accumulator voltage is lower than, the charger offers very little tiny stream IT to charge, IT is generally about 0. 01C C is the battery capacity The state 2: Constant current is charged.

It can be at the time of the voltage UT to reach and charge enabling in the voltage of the storage battery, the charger offers a high-current I BULK to charge constant current to the storage battery, this stage charged takes stage, the end of storage battery is sharp in voltage build up, enter constant voltage charge stage until voltage build up has been to press the charging voltage UOC.

The state 3: Constant voltage charge.

At this stage, the charger offers a voltage UOC slightly higher than the rated value of the storage battery to carry on the constant voltage charge, the charging current of the circuit will be reduced gradually according to the index law, until the electric current magnitude means charging and stopping the electric current I OCT about 10 IBULK ,The storage battery has already been filled, the charger enters the floating-charge charging state.

The state 4: Floating-charge is charged.

Floating-charge charges stage, the charger offers the floating charge voltage UF to flow and charge to the storage battery by very little float charging, in order to remedy the capacity losses that the self-discharge of storage battery causes. Vary with temperature because of the floating charge voltage of the storage battery at the same time, need to choose the thermal resistor of the temperature coefficient the same as storage battery to carry on temperature compensation, guarantee that can charge floating-charge at any temperature with the rigorous floating charge voltage. The temperature coefficient is generally chosen- 3. 5~ – 5 mV/ .

3 charges circuit design

Fig. 2 shows in order that because of U C3909 solar energy battery charger circuit block diagram, the photovoltaic array is sampled and feedbacked the digital signal to the one-chip computer by the analog to digital converter again through the electric current of voltage, the one-chip computer outputs PWM signal to drive PMOS tube according to the operating condition of the photovoltaic array, realize the maximum power tracing of the photovoltaic array. Super condenser bank, DC/ DC converter, UC3909 are used for realizing four stage charge control to the valve controlled lead-acid battery, and utilize the super and capacitive characteristic to optimize the charging/discharging process. This text lays particular emphasis on realizing partly to super condenser bank, U C3909 and DC/ DC converter,etc. that analyzes and designs to the charging at four stages of the valve controlled lead-acid battery.

System block diagram of Fig. 2

3. Main parametric design of 1 UC3909 charger

Based on UC3909 to fill the discharging circuit and is shown as in Fig. 3.

Fig. 3 based on UC3909 serves as the discharging circuit

According to integrated circuit and photovoltaic array within UC3909, and super electric capacity parameter combines the capacity of the valve controlled lead-acid battery and isoparameter of nominal voltage to design rational calculation to each part of the circuit. Originally design using 12 V that Saite Company produced, 65 Ah colloidal sealing lead-acid storage battery, according to the accumulator charge parameter that the producer offers, the floating charge voltage UF fetches 13. 8 V, can make to charge the voltage UT fetch 10. 8 V; Overvoltage charging voltage UOC 14. 7V; The tiny stream charging current I TC fetches 0. 26 A; Constant current charging current I BU LK fetches the systematic maximum charging current 6. 5 A; Overcharged to stop the electric current IOCT fetching 1 A.

In addition, may follow and flow into the fixed control current ITRCK of the reverse Ausgang CA of error amplifier of the electric current within U C3909, the intersection of tiny stream and the intersection of charging current and I T, the intersection of constant current and the intersection of charging current and IBULK and overcharged to terminate the electric current IOCT calculating and obtaining RG1, RG2, R OVC1 and ROVC2, their basic formulae are as follows:

It is installed outdoors that the lead-acid battery in the photovoltaic system is generally stiff with the solar energy, and the change of ambient temperature has great influence on characteristic of the lead-acid battery, research indicates, 10 of every change at the extremely sensitive temperature of the temperature flows in the float charging of the lead-acid battery, float charging flows and doubles and redoubles, as to the storage battery used in this design, according to the parameter which the producer offers, the same float charging flows, its temperature coefficient is – 3. 9 mV/ Centigrade degree, that is to say that if prevents float charging from flowing and increasing, when the temperature raises 1, its floating charge voltage should be reduced by 3. 9 mV ; The same, when the temperature is reduced by 1, its floating charge voltage should raise 3. 9 mV could keep float charging flowing constantly.

Compensator circuit of 4 lead-acid batteries of temperatures of Fig.

Have integrated the circuit with temperature compensation function of the lead-acid battery and is shown as in Fig. 4 within U C3909, A1 is the electric current / voltage transition element, its input end connects 10 k ordinary resistance and 10 k thermal resistor respectively. A2 and connecting four pieces of 20 k resistance to make up the amplifying circuit of differential operation. RT HM is generally stuck to the surface shell attached to lead-acid battery to use for measuring its temperature, while holding the temperature variation of battery inner in lead acid, enable the reference voltage 2 of U C3909 through the feedback of the thermal resistor RTHM. 3 V presses with the temperature too- 3. 9 mV / temperature coefficient change in . Thus guarantee the lead-acid battery works in the safe floating charge voltage accurately in floating-charge state, have protected the lead-acid battery.

3. 3 DC/ DC converter designed

Because the photovoltaic array receives the external environment of great impact, the excursion of the stiff output voltage of solar energy of 12 V is about 020 V in this system, if directness is the lead acid accumulator charge, because the normal working voltage of the lead-acid battery should be higher than 10. 8 V, so when under the pale condition, the solar energy stiff output voltage is lower than the terminal voltage of the lead-acid battery, whether its electricity produced can be absorbed by the lead-acid battery. So system this adopt, make solar energy stiff to export, undergo super bank of capacitors, and then from behind the super bank of capacitors, through going up and down and pressing first as the lead acid accumulator charge, the effective enhancement system is pale to charge ability, raise utilization efficiency.

Originally design adopting and hoisting or lower and pressing the mode, as shown in Fig. 5, the input end of montage DC/ DC chance-over circuit of the super capacitor, presume the input span is 4. 520 V, it is 10 to export the voltage range. 8~ 14. 7 V.Q1 is outputted PWM signal to control by the one-chip computer, Q2 is driven circuit control by the MOS tube by 5 feet of UC3909, it is determined by foot electric capacity CT that connecting resistance RSET and 19 base pins connect 18 of UC3909 that 5 feet output PWM frequency, the formula is as follows:

Fig. 5 DC/ DC chance-over circuit

The operating frequency of UC3909 sets as 200 kH z. and returns the electric current of tandem connection to sample the resistance RS in the charging loop of the storage battery at the same time, the voltage signal of RS both ends is connected to CS separately as the input signal that the electric current samples the amplifying circuit within U C3909 chip, CS input end, considers the charging current is relatively big, prevents the electric current within U C3909 chip from sampling the saturation distortion of amplifying circuit at the same time in order to reduce the power consumption of RS, RS should try hard to be small, fetches 55 m in this circuit.

3. 4 super roles in system of bank of capacitors

1 The super electric capacity has long performance life, charge and discharge and limit little, power density is great, the specific energy of the rechargeable battery is high, such advantages as very fast heavy current charges and discharges, it is a new kind of efficient stored energy devices. But because its energy density is only 1/ 5 of the lead-acid battery, it is unable to respond to the request that the solar energy street lamp lighted high-capacity stored energy of circuit system of this kind of high-power. So adopt the accumulator battery to mix stored energy with super bank of capacitors in this system, combine the high watt density of the super electric capacity and high characteristic of energy density of lead-acid battery, improve the system performance of stored energy.

2 Adopt 8 in this system One is 2. 7 V, the super electric capacity of 1 200 F connects in series into nominal voltage 21. 6 V, the super bank of capacitors with capacity of 150 F, because 12 V solar energy is stiff during strong light-struck its output voltage is about 20 V, adopt 21. 6 V super bank of capacitors can already ensure the safety of stored energy device and can fully absorb the stiff energy output of solar energy at the same time.

3 Because system realize maximum power output, high-speed feed-through and shut off, will both produce and interfere with the harmonic wave on the Ausgang correspondingly of MOS by MPPT technology, can add super bank of capacitors valid the intersection of barrage jamming and harmonic wave among the intersection of solar energy and stiff Ausgang and lead-acid battery, guarantee the lead-acid battery charges and discharges steadily, lengthens the life time of the lead-acid battery.

4 The lead-acid battery can only work in UOC voltage range in UT take 12 V lead-acid battery as examples, can only work in 10. 8~ 14. Among 7 V . By contrast, because the super bank of capacitors can discharge deeply, its working voltage can be presumed in the lower range, the lowest output voltage is 4 as presuming super bank of capacitors in this system. 5 V. is in pale condition, the solar energy stiff output voltage will be higher than the super terminal voltage of bank of capacitors, guarantee that exporting the electric energy is absorbed and stored by the super bank of capacitors, and then press circuit switching to export to the lead-acid battery from going up and down, namely has realized the pale charging function.

5 Because the charging condition of the lead-acid battery is extremely strict, under not charging stage with four of storage battery, the electric quantity of its enable input is different, the output that and the solar energy is stiff is influenced by external environment and change greatly. It is big when acceptable input electric quantity under the working condition at present of the lead-acid battery in the stiff electric quantity that exports of solar energy, some surplus energy will be kept in the super bank of capacitors; On the contrary, when the stiff electric quantity that exports of solar energy is smaller than the input electric quantity that the lead-acid battery can accept, electric quantity that store can the undercompensation is exported to the lead-acid battery in the super bank of capacitors. So can already guarantee the charging steadily of the lead-acid battery, the increase of service life, also can raise the system utilization.

3. 5 experiment emulation

Such as Fig. 6 It is 4 to show in order to look on in protues simulator as the super terminal voltage of bank of capacitors. U C3909 5 the intersection of foot and output pulse and output waveform of DC/DC at this moment at the 5 V. Emulation reveals, 5 foot output frequency is 200 kHz, the output of DC/ DC chance-over circuit is comparatively smooth, and the voltage amplitude is 13. 6 V, belongs to and presumes that exports the voltage range, basically conforms with surveying the result, prove the system can realize the pale charging function.

4 concludes the speech

This system adopts the super bank of capacitors to make the street lamp lighting systems of solar energy and mix the storing energy component with the lead-acid battery, utilize the super bank of capacitors and go up and down and press the pale charging function of the circuit implementation, raise the stiff utilization factor of solar energy effectively. Four stages making use of U C3909 to realize the lead-acid battery at the same time charge and manage, lengthen the life time of the storage battery, raise system stability and service efficiency.